The present invention relates to continuous or staple bicomponent filaments or yarn used in knitted, tufted, flocked, woven or nonwoven quality textile products requiring a soft hand or soft feel.
Synthetic fibers are continuing to grow, in the field of textiles due to needs of expanding world population and the limited availability of natural fibers such as cotton and wool. Cotton, silk and wool use is growing but at a much slower rate due to the naturally occurring constraints that these fibers bring with them. Some of these constraints are the growing seasons, the available land for crops and animals, and the harvesting of these natural fibers. Consequently synthetic textile fibers are rapidly expanding to fill the ever growing needs of the marketplace.
One of the problems that face these textile manufacturers is the need for these synthetic fibers to be soft to the touch if the end use is for clothing or home furnishings. People want a soft feeling product. In order to make synthetic fibers feel soft the manufacturer must make the fibers into very small deniers similar to naturally occurring fibers. Some manufacturers are even producing micro fibers as taught by Park et. al. in U.S. Pat. No. 4,460,649 that are smaller than natural fibers.
The small denier size of the fibers puts additional constraints on the manufacturer because it takes more equipment and more time and consequently more money to produces these small fibers. It would be an economical advantage if the manufacturers could increase the denier of the filaments and still keep the soft desirable feel or hand. Presently no one has suggested a way to increase throughput by increasing the denier size and retain the soft feel of smaller denier filaments.
This invention teaches how to manufacture a large denier sheath core bicomponent synthetic filament that has the hand and soft feel of a small denier filament. Through the use of bicomponent sheath core technology the inventors produced an 18 denier bicomponent filament that has the same feel as a 5-6 denier homopolymer filament.
This large soft feeling bicomponent filament would be excellent for use in the manufacture of textile outerwear such as coats, jackets, and sweaters scarves etc. as well as an home furnishing, upholstery or knitting yarns. Anyone skilled in the art would vary the dnier size and sheath percentage to suit the end use for a soft yarn.
A yarn whether natural or synthetic, is composed of many filaments. Each filament is measured and assigned a denier size. Naturally occurring filaments such as silk or cotton usually occur within a given range of filament sizes. A cotton filament is usually 1.5 denier and silk is usually 1 denier. Wool ranges in size and is determined by the type of sheep that it comes from. Carpet wools are course and measure in the 15 to 20 denier range while softer wools are in the two to six denier range. A denier is a measurement well known to those skilled in the art. As previously stated Synthetic filaments are extruded and textured to mimic or mirror natural filaments. Recently, great strides have been made in manufacturing machinery that can extrude micro denier sizes of from 0.5 to 3 denier filaments. The machines are costly and do not produce massive quantities of filaments without a great deal of capital investment. The synthetic filaments produced are pleasing to the touch and are used alone or in blends to create yarns that are extremely soft and have a silky "hand" or feel.
Almost all of the micro denier synthetic filaments are produced by extruding molten polymer through tiny holes in spinnerets. The size of the hole combined with draw ratio determines the denier of the filament. The smaller the denier size that is extruded the softer the yarn comprising a bundle of these small denier filaments will be. A synthetic yarn comprising a bundle of 35 filaments of 1.5 denier each will feel like a natural cotton yarn to the touch. Various other factors such as spin finish and water absorption ability will also affect the feel or hand of the yarn. These yarns are classified as textile yarns as they are well suited to clothing and home furnishings fabrics and not carpets or industrial yarns.
A bundle of synthetic filaments are extruded as continuous filament yarn or as many ends of filaments called staple tow which is drawn, crimped cut into lengths similar to those naturally occurring in cotton. The cut staple is then spun into a yarn size to suit the end use that was intended by the textile manufacturer. Larger yarns such as a 8/1 cc cotton would be used in bath mats or course upholstery fabric while a 30/2 cc cotton would be used to make a textile fabric suitable for clothing.
Soft yarns are woven, tufted, flocked, needlebonded, calendered, or knitted into a textile cloth or fabric to satisfy the appropriate end use.
Lin Fa Lee U.S. Pat. No. 3,992,499 shows the possibility of extruding two filaments of differing dyeability using a sheath core system of feeding two molten polymers of differring dye affinity to a special spinneret. The patent teaches how to dye heather effects for apparel by varying the amount of polymer having differing dye receptors. The yarn sizes in each example are tiny deniers useful in the manufacture of textile products.
Ando et al. U.S. Pat. No. 3,551,279 uses sheath core bicomponent tiny filaments with varying amounts of titanium dioxide in either the sheath or the core or both to create a difference in luster's of light reflection when woven into a fine apparel or fabric.
Both of these patents teach using bicomponent technology to get a special effect in a textile yarn but do not teach or infer how to produce a soft feeling bicomponent textile yarn made from large denier sizes.
Present technology of machine engineering allows for a much smaller denier or apparent denier by separating a sheath and a core as is shown in Park et al. U.S. Pat. No. 4,460,649). This patent shows that a composite fiber consisting of two components such as a polyamide and a polyester wherein the two components can be separated into a plurality of microfibers by chemical and physical treatments. A 70 denier 20 filament yarn was separated to yield an apparent 5 denier per filament yarn which was suitable for a woven cloth possessing the attributes of artificial suede. Park is trying to make the fibers extremely small in order to get a desirable feel and other associated benefits not make a large denier yarn that feels soft.
Other techniques called "island in the sea" extrusions also produce mircro deniers. The equipment used to manufacture the filaments is expensive and the texturing process called false twist texturing is also very expensive.